1. Field of the Invention
The present invention relates to recording apparatuses such as printing apparatuses and image forming apparatuses, and in particular to recording apparatuses capable of performing recording on recording media of various thicknesses by appropriately adjusting a gap between a recording unit, such as a recording head, and any of the recording media.
2. Description of the Related Art
In a general recording apparatus that performs recording on a target surface of a recording medium while moving a recording head back and forth along a guide member, it is desirable that parallelism between the target recording surface and a surface of the recording head be adjusted with high accuracy. To appropriately perform recording on recording media having different thicknesses, it is also desirable that a gap between the recording head and the target surface of any of the recording media be maintained in an appropriate manner even if the thickness of the recording medium, such as paper or the like, is changed.
There are various recording media proposed as a target of recording performed by recording apparatuses such as printing apparatuses and image forming apparatuses. Exemplary media of small size and having relatively large thicknesses include compact discs-recordable (CD-Rs), digital versatile discs (DVDs), and cards (which are hereinafter collectively referred to as CDs). In known general-purpose recording apparatuses, use of a conveying path for cut paper in performing recording on a CD, for example, triggers problems in that the CD is not conveyed appropriately or is damaged with scars because of high rigidity of the CD, or the CD cannot be conveyed because of the distance between conveying rollers. To avoid such problems, when a small-sized recording medium having a large thickness such as a CD is conveyed, the medium is fed with a dedicated tray and is conveyed therewith along a conveying path different from the conveying path for cut paper.
In general, a tray dedicated for performing recording on a CD has a thickness of about 3 mm. In contrast, cur paper such as glossy paper for photographic printing has a thickness of about 0.25 mm. To appropriately perform recording on various recording media ranging from glossy paper to CDs, a gap adjusting mechanism capable of adjusting the gap between the recording head and the recording medium within a wide range of about 3 mm is required.
A recording apparatus capable of accommodating various paper thicknesses while maintaining parallelism between the surface of a recording head and the target surface of a recording medium is disclosed in U.S. Pat. No. 6,899,474. Referring to FIG. 15, in the recording apparatus of U.S. Pat. No. 6,899,474, when an eccentric cam 521 fitted to a guide shaft 52 serving as a guide member is rotated, the guide shaft 52 is moved vertically in a direction A in which the gap between the recording head and the recording medium is adjusted, whereby a carriage 50 having a recording head 55 is guided in a vertical direction B. In this case, a controlling guide member 114 that controls the posture of the carriage 50 is provided in such a manner as to have the surface thereof being parallel to the direction in which the gap is adjusted. Thus, the aforementioned parallelism is maintained and capability of accommodating various paper thicknesses is realized.
Another recording apparatus is disclosed in U.S. Pat. No. 6,315,468. This recording apparatus includes a plurality (two, for example) of guide shafts that guide the movement of a recording head. The guide shafts are provided at respective ends thereof with eccentric cams. These eccentric cams are rotated synchronously, whereby the plurality of guide shafts are synchronously raised and lowered. Thus, the parallelism between a recording medium and the recording head is maintained.
In the recording apparatuses disclosed in U.S. Pat. Nos. 6,899,474 and 6,315,468, however, it is difficult to provide a simple configuration that realizes reduction of both the size of the apparatus body and the manufacturing cost.
Specifically, in the recording apparatus disclosed in U.S. Pat. No. 6,899,474, the controlling guide member controlling the posture of the carriage needs to have a surface parallel to the gap adjusting direction so as to maintain the parallelism between the recording medium and the recording head. Moreover, the controlling guide member needs to be provided at an appropriate distance from the guide shaft for the purpose of securing stable movement of the carriage. That is, the controlling guide member needs to be provided above a region where the carriage moves. This results in a restriction in terms of the height of the apparatus (see reference numeral 114 in FIG. 15).
On the other hand, the recording apparatus disclosed in U.S. Pat. No. 6,315,468 includes a plurality of movable members, the guide shafts, used for gap adjustment. This results in complexity of the mechanism for driving such members. Moreover, in terms of maintaining the parallelism between the recording head and the recording medium, it is difficult to obtain high accuracy because the recording head is positioned with a plurality of cams. Consequently, image quality tends to be deteriorated.